1. Field of the Invention
The present invention relates to improving the properties of phenol-containing streams, such as coal liquids and petroleum asphaltenes, by oxygen-alkylation. The resulting upgraded stream has improved storage and processing properties.
2. Description of the Prior Art
The viscosity of phenol-containing hydrocarbonaceous streams such as coal liquids and petroleum asphaltenes generally increases with time, thereby presenting stability problems in the storage and use of such liquids. Many of these liquids are rich in heteroatoms, and especially organic oxygen such as phenolic and carboxylic oxygen. It is believed that increases in molecular weight and consequently in viscosities are brought about in two ways: (1) by hydrogen bond formation and (2) by free radical initiated polymerization. The instability of streams is evidenced by increasing color intensity with time--mainly owing to the presence of phenols.
Furthermore, because streams such as coal liquids are generally rich in phenolic and carboxylic functionality, they are highly polar and not compatible with less polar petroleum liquids of comparable boiling point range. Thus, segregation occurs because the petroleum liquids, which lack highly polar groups, cannot participate in the intermolecular association between adjacent coal liquid molecules.
Although various attempts have been proposed to eliminate or at least alleviate the aforementioned problems, there is still a need in art to develop more efficient and economical ways of achieving stability in such liquids.